In the typical commercial dialyzer arrangement, particularly in the case of hollow fiber-type dialyzers positioned in a tubular housing, the dialysis solution inlet is positioned vertically lower than the dialysis solution outlet of the dialyzer. Correspondingly, in the case of hollow fiber dialyzers, this requires, for the optimum counterflow arrangement, that the blood inlet be positioned vertically higher than the blood outlet.
The reason for the above arrangement is that the bubbles which may pass into the dialyzer through the dialysis solution flow path can be swept out of the dialyzer in a much more effective manner if the dialysis solution outlet is positioned vertically above the inlet. In the opposite circumstance, bubbles may collect in the dialysis solution flow path, which interferes with the dialysis efficiency of the device.
In this conventional circumstance, where the blood flows downwardly, typical dialysis arrangements have called for an upstream bubble trap in the blood flow line, to keep air out of the blood flow path of the dialyzer, to avoid air blocking of the membrane flow channels, which can take place because of the natural buoyancy of air, which tends to try to rise against the downwardly-flowing current of the blood.
Also, a downstream bubble trap must be provided in the blood flow circuit of the dialysis system for safety, since it is imperative to avoid the infusion of air bubbles to the patient.
In accordance with this invention, an improved dialysis system is provided which permits the elimination of one of the bubble traps in the blood flow circuit, which of course results in a significant cost savings in each dialysis procedure.
The invention of this application takes advantage of improved dialysis delivery system techniques to permit the simplification of the dialysis system resulting from a downward flow path of the dialysis solution through the dialyzer.
Furthermore, the system of this invention may be simplified for the user by providing a bubble trap which is integral with the dialyzer unit, carried at the outlet of the blood flow path from the dialyzer, for greater ease of setup by the user.